Module 19

• Shadow - dark area that forms when an opaque object blocks light from a light source
• Opaque - does not allow light to pass through them
• Transparent - allows light to pass through them
• Translucent - light partially passes through the object
• Umbra - darkest and central part of the shadow
• Penumbra - lighter outer (marginal) part of a the shadow
• Antumbra - similar to penumbra, but forms where the umbra ends
• Antumbra - solely exists if the light source has a larger diameter than the opaque object
• Shadow bigger (blurry) -> farther
• Shadow smaller (sharper) -> nearer
• Light source lesser than the object, umbral region is greater than the penumbral region
• Greater diameter of the light source compared to the object, the greater penumbral region is cast
• Syzygy - alignment of 3 celestial bodies such that 1 body is directly between the other 2
• Examples of Syzygy

  • Sun
  • Moon
  • Earth
• Eclipse - temporary alignment of celestial bodies in space that causes 1 object to obsecure another, either partially/completely, form an observer's prespective
• Solar Eclipse - occurs when the Moon passes between the Sun & Earth, casting a shadow on Earth that either fully/partially blocks the Sun's light in some areas
• The moon's orbit is tilted
• 3 Types of Solar Eclipse

  • Total
  • Partial
  • Annular
• Total - observer is within the umbral shadow of the moon cast on earth
• Total - sun appears completely obstructed by the moon
• Partial - observer is within the penumbral shadow of the moon cast on earth
• Partial - sun appears partially obstructed by the moon
• Annular - observer is within the antumbral shadow of the moon cast on earth
• Annular - observer is within the antumbral shadow of the moon cast on the earth
• Annular - sun appears as a ring obstructed by the dark moon at its middle
• Perigee - closest to the Earth
• Apogee - farthest from the Earth
• As distance decreases, apparent size increases
• Lunar Eclipse - occurs when the Moon moves into the Earth's shadow
• Lunar Eclipse - only occurs when the Sun, Earth, Moon are exactly/closely aligned with Earth between the other 2
• Lunar Eclipse - only on the night of a full moon
• Blood Moon - totally eclipsed Moon
• Blood Moon - reddish color, which is caused by Earth completely blocking direct sunlight from reaching the Moon
• 3 Types of Lunar Eclipse

  • Total
  • Partial
  • Penumbral
• Total - moon is at the umbral shadow of earth
• Partial - moon enters the umbral shadow of earth
• Partial - moon appears slowly diminishing on one side
• Penumbral - moon is within the penumbral shadow of earth
• Penumbral - moon appears less brighter than usual